Hey guys Getting a forged bottom end build Wiseco 87.5mm pistons and Eagle rods. Now what are ideal piston to bore clearances? Wisecos come with a recommended 0.0025", now the guy who is building my engine believes this is a bit tight for forged pistons. I told him I will eventually want the 350-380rwkw 20-24psi oof boost. He recommends going to 0.0035" of PtoB clearance, what are people opinions on this? Would like to hear from those who have done this and what there piston to bore clearances are? He also told me that any motors he builds for drag/circuit cars he doesn't go anything less that 0.004" - again variables on different pistions and silicon content. Really only want to do this once and do it right! Thanks Matt.
the wiseco are coated, so there's already more than 0.0025 thou of clearence, but he's not wrong, i'm an engine reconditioner and i do the same with drag/high boost engines, i'll build mine in the next few months and i'll probably go aroun .0005-.001 of extra clearence
the black on the skirt is a coating and it's there that you get the clearance, usually just at bottom end of the pin bore
Now, I personally believe that in anything short of a circle track race car, forged pistons are a woftam and totally unnessesary. Even up to insane rpm and power outputs. ESPECIALLY in a force-fed engine. NEVER EVER again will I waste my money on forged clobber. However, metalurgy and forged piston technology has come a fair way from the days of old with rattling and smokey pistons at anything apart from red hot and they are capable of running much closer clearances and so much quieter and less smokey than the older generation of "forgies". Wiseco have been in this game for a long time, if they reccommend a certain clearance, then why would you question the manufacturer to bore up to some funky setting that was once relevant, BUT went out with the ark? The clearances they specify are relevant to THEIR pistons only and should never be applied to another brand that may still be manufacturing to the "olde waye"!! No way in hell i would set the piston clearances wider than what is reccommended which basically results in a partially worn out engine BEFORE you even start it.......... Cmon men, out of the dark ages gents and into the brave new world. Why not speak to the manufacturer before making any dodgey decisions. L8r E
yep pretty much irrellevant of who the engine builder is.. piston clearances are stated by the manufacturer for their pistons . wiseco's 25 thou with side coatings (preferably with torque plate ) or 30 thou without coatings
pistons' manufacters only mark the minimum clearence, and they also write to give them extra clearence depending on the application...
Can anything go wrong with the recommended 0.0025"? Reason I went forgies is the price quite cheap and you're getting brand new pistons not 20 yr old stuff. What's the reason of going larger clearances, heat expansion?
unlimited headjobs ..I went to tech with Matt What people dont know about wiseco's for the Z32 is that back in the early to mid 2000 there were big issues with wiseco's and the VG ...from piston diameter sizes,silicone content,heat expansion/piston shape,smoking issues etc . Ashspec/Z1 worked with wiseco and corrected all these issues . This is the reason Z1 has the best price for coated wiseco pistons on the market today. grab the torque plate I used from UAS and go .0025 with the wisecos as I did. you wont be running bigger boost than me (it is on the tight side of clearance but thats why you use a torque plate to ensure perfectly round bore .. engines loosen up as they run in not get tighter) if it helps you sleep at night ..nothing wrong with .0030
Matt is building my motor, I was planning to get the torque plate for honeing, not needed for boring is it? I got my wiseco's from coz if that matters.
i haven't any wiseco in the workshop at the moment, but this is basically what's in all forgies... they only suggest minimum clearence, you're going to add 3 times the original boost and 2 times the hp in your engine, i wouldn't mind to add a little bit of extra clearence, also because you won't have warranty on these, and .0005-.001 more than the minimum clearence is not like having a worn engine, come on...
I used these pistons 2 years ago, I run between 14-18 psi have had no trouble, my clearence is Wiseco recommended just run it in properley on low boost before you turn it up. I have done 40k since rebuild.
Yeh going to stick to the 0.0025, it's only going to be a weekend street car with an occasional track day in which again only for fun, not looking to break any records.
Good to hear Matt Exactly what you want for your build, nothing worse than piston slap on cold start up.
